Shrink-film capping machine

ABSTRACT

An automatic shrink-film capping machine for forming and applying caps of shrink-film to the open mouths of containers. This device comprises means to advance, cut and position a sheet of shrink-film over the top of a container. A positioned sheet is engaged by a capper head which is lowered relative to the sheet and container whereby heating elements, disposed therein are moved radially inwardly and contact the shrink-film and container to form a heat shrunk cap thereover.

[111 3,783,582 Jan. 8, 1974 United States Patent [191 Willvonseder m Y E% m k Cdw A u m Mdf a um m wM w A m m m mmm mEA J KR mm w Sim MN ..DW.

[22] Filed: Nov. 30, 1972 [21] Appl. N0.: 310,978

[57] ABSTRACT An automatic shrink-film capping machine for forming and applying caps of shrink-film to the open mouths of containers. This device comprises means to advance, cut and position a sheet of shrink-film over the top of a container. A positioned sheet is engaged by a capper head which is lowered relative to the sheet and container whereby heating elements, disposed therein are moved radially inwardly and contact the shrink-film and container to form a heat shrunk cap thereover.

Y 12 3/ /7 7 3 ,3 3 b 7 5 07 6 M B i. 3 22 3M 32 5 M 0 7' 2 m m2. 3 m3 5 "5 u m mml "m8 m m mm .u r 6 m mw ll f3 C 5 5 M ..U IF 1 1] 2 8 w U [56] References Cited UNITED STATES PATENTS 1,824,384 9/1931 Tevander.............................. 3,0l7,729 1/1962 Cheeley 8 Claims, 9 Drawing Figures PATENTEU JAN 8 I974 Yes SHRINK-FILM CAPPING MACHINE This invention relates to an apparatus and method for applying heat shrinkable film covers to cups or other containers.

Methods and apparatus for applying shrink-film covers to receptacles are known. These devices have proven to be either too expensive and too slow for a small counter-top type of operation, or inefficient in that the covers formed are not always uniform to thus be leakproof. Typical methods of sealing have involved the blowing of heated air around a sheet of shrink-film, or applying a flat heater plate directly to the top rim portion of a cup with a sheet of waxed paper placed thereover so as to bond the closure thereto by the melting-fusing principle. In the case of the former, a rather bulky, slow operating and expensive unit is required, while in the case of the latter, any uneveness or lack of uniformity in the top of the cup results in an imperfect sea] at the lowest point in its circumference.

It is therefore, an object of this invention to provide an inexpensive and fast portable unit for readily and speedily capping cupsand other containers with heatshrink-film.

It is another object to provide a capping apparatus which makes a uniform and relatively large seal around the periphery of the container being capped.-

A further object is the provision of an apparatus having a shrink-film capper head with movable heated segments extending circumferentially thereof to sealingly engage a sheet of film deposited on the top of a cup or other container.

A still further object is to form and snugly apply a cap of shrink-film over the top of a container with the cap being heat shrunk in a .relatively uniform wide band around the periphery of the cup at a level below its rim.

These objects are realized in accordance with the present invention by providing a shrink-film capping machine with an improved capper head design. Basically, the inventionconsists of a machine which includes a roll or other source of shrink-film 'which is automatically unwound, cut, and positioned over the top of a cup to be capped. A capper head, having contoured heating elements adapted to move radially inwardly is lowered over the uncapped cup and sheet'of shrink-film, and a cap is formed by causing the heating elements to engage and move the sheet of film against .the side wall of the container.'Because of the direct contact of the heater elements and the shrink-film, a quick and positive shrinking ofthe film is accomplished. In addition, the shrinking of the film relative to the wall of the cup, as opposed to heat sealing the film directly to the top rim of the container with a flat heater element, results in a cap which is more durable and leak-proof, in that the film is folded snugly over the rim and adheres to the contour thereof. Thus, sealed cups may be readily and uniformly stacked with less likelihood of being'upset. As the capper head mechanismfolds the film over the rim of the cup and heat shrinks a circumferential band of the film around the outer periphery thereof, the cap is merely shrunk around the top of the cup and need not become sealed to the surface of thecup itself. Thus, the-film closely conforms to the contour of the rim and provides an effective seal for liquids contained therein.

These and other objects-and advantages will become apparent from the accompanying .description and drawings, wherein:

FIG. 1 is a perspective view of a shrink-film capping machine constructed in accordance with the present invention;

FIG. 2 is a side elevation of the machine illustrated in FIG. 1;

FIG. 3 is an enlarged exploded view of the shrink-film capper head; 1 g

FIG. 4 is a bottom plan view of the shrink-film capper head, illustrating the heating elements in their'open, non-operative positions;

FIG. 5 is another bottom plan view, similar to FIG. 4, but showing the heating elements in their closed, operative positions; I I v FIG. 6 is a-partial cross section of the capper head in raised, non-operative position, relative to a container;

FIG. 7 is a view, similar to FIG. 6, illustrating the capper head in lowered, operative position, relative to a container;

FIG. 8 is a side elevation view illustrating one embodiment of the heating element actuating means; and FIG. 9 is a sectional viewof a heating element, taken along line 9-9 of FIG. 8.

Proceeding next to the drawings, wherein-like reference symbols indicate similar elements throughout the several views, a specific embodiment of the present invention will be described in detail. I

,In FIG. 1, there is illustrated an automatic shrink-film capping machine 10 constructed in accordance with the present invention. A generally C-shaped housing forms the frame of the machine'and is provided with a relatively flat bottom support bed 11, an upstanding rear frame wall 12, and a cantilevered top support arm 13. It will, of course, be understood that the frame may assume other configurations, such as, T-shape A roll or other supply source of plastic shrink-film 14 may be suitably housed within machine 10 and the film web may be cut into individual cap forming sheets 14 by suitable severing means, suchas, knife 15 positioned over and extending across the entire width of the unrolled film web. It will be understood that the severing mechanism may be otherwise located and constructed. For example, a fixed knife may be arranged generally in line with the capper head and an upper knife may be arranged on the head so as to be movable therewith to sever the film during travel of the capper head. The front portion of the support bed 11 is recessed,.as at 11', so as to better receiveand vertically position a cup 16 or other container to be capped by the apparatus. As shrink-film capper head 17 is located in the front portion of support arm 13 above and in axial alignment with a container pedestal 18 in recess 11' upon which a 'cup 16 to be capped is placed. Suitable motorized actuating mechanism (not shown) which reciprocates the capper head from a raised, non-operative position to a lowered operative position and back again, is contained in capper head motor housing 19. t 1

. Referring again to roll 14, it will be seen in FIGS. 1 and 2 that it is supported for free rotation by shaft 20 in suitable L-brackets 21 attachedto the rear of machine 10 on bed 11.Extending longitudinallyalong the sides of bed 11 are suitable film gripper housings 22 in which are mounted reciprocating film'grippers' 23 and 24, automatically operated by a motor mechanism (not shown) in support bed 11. These grippers suitably engage the edges of the web and move suitable reciprocating gripper rods 25 in and out of gripper housings 22 via a flexible roller chain, a geared arrangement, or

other suitable actuating means, not shown. The specific means to impart movement to the plastic web to move it into position over the open mouth of the container may assume various generally conventional forms which do not constitute a part of this invention.

Briefly, the operation of the capping machine will be apparent by referring to FIGS. 1 and 2. With an electrical lead 26 connected to a source of electricity, not shown, and a suitable operating switch 27 turned to the on position, the machine is ready for operation after a suitable warm-up period. With current flowing through electricity conductors 28 into the capper head, the heating elements thereof will always be maintained at desired operational temperatures. When a cup 16, is arranged on pedestal 18, its weight may be sensed by micro-switch 18A (see FIG. 6) to actuate the motor mechanism and begin the cycle of the machine.

Thus, the two sets of gripping fingers 23, 24 grip the roll of shrink-film and move it towards the front of the machine in a position directly over the mouth of cup 16. When the gripper rods 25 are extended to their maximum operational length, a suitable limit stop (not shown) contacts a-second suitable micro-switch (not shown) and simultaneously actuates the shrink-film knife blade and the capper head mechanism 17. With the shrink-film cut and held in place as a single sheet 14', the capper head motor mechanism begins to lower the capper head 17 vertically in the direction of cup 16. A suitable sensing switch (not shown) within capper head 17 limits the further downward movement of capper 17 when it comes into contact with the cup 16. Thus, the machine is adapted for use with cups of various sizes.

As the capper head 17 approaches the end of its downward travel, it pulls and disengages the sheet 14 from the grippers 23, 24 and folds it down and circumferentially of the cup. When the capper head 17 is in this lowered operative position, the heater elements 36 therein are moved radially inwardly to contact and press the shrink-film against the sides of thecontainer. The film, of course, shrinks when subjected to heat and pressure and an effective cap is molded around the top of the cup 16. The heating elements are held in their working position for a period of several seconds which may be adjusted by a suitable timer 29, depending upon the type of container and shrink-film used. Once the shrink-cycle has timed out, the heating elements are retracted and the capper is raised to its non-operative position. The capper machine is then ready to recycle when another cup is placed on the container pedestal.

Referring now to FIG. 3, an exploded assembly view of the capper, illustrating all of its working elements, may be seen. The capper head 17 is suspended from the top of the machine 10 by vertically extending rods 30 connected to and depending from the upper portion of a flat top plate 31, shown as square in this embodiment, but which may be of any desired shape. Attached to the bottom side of plate 31 are four spacer blocks 32 which in turn suitably support a bottom flat plate 33. This arrangement provides channel spacers 34 between the side walls 35 of blocks 32 when the plates are interconnected. Spaces 34 form radial guideways for the movable electric heating elements 36', connected to a source of power by conductors 28. The movement of heating elements 36 are limited by stop pins 37, on the top and bottom faces thereof, which ride in radial grooves 38 and 39 in top and bottom plates 31 and 33,

respectively. In the embodiment shown, four heater elements 36 are used, however, a fewer or greater number may be used depending upon the requirements of the container to be capped.

The actuating mechanism for moving the heating elements radially may consist of a ring 40 rotatably secured to bottom plate 33 by screws or the like 41 and washers 42. Upstanding actuating pins 43 are spacedly secured at generally right angles to the rotatable ring 40 and are arranged to pass through spaced circumferential slots 44 in bottom plate 33, and communicate with diagonal slots 45 in each of the heater elements I 36. Thus, rotary motion of ring 40 is translated into straight line radial motion of heater elements 36 sliding in channels 34.

As will be apparent by referring to FIGS. 3, 4 and 5 and as viewed from the bottom of the capper head 17, when ring 40 is rotated in a clockwise direction, actuating pins 43 ride in diagonal slots 45 and serve to move the heating elements radially outwardly. Conversely, when the ring is rotated in a counter-clockwise direction, the heater elements move radially inwardly.

While ring 40 may be rotated by various means during the cycling of capper head 17, this may be accomplished in the embodiment illustrated in FIG. 8, wherein actuating lever 48 of rotatable ring 40 bears against the inclined face 47 of upstanding cam bar 46 under the tension of a spring 49. The latter has one end attached to actuating lever 48 and the other end secured to element 50 on capper head '17. It will be understood, however, that other spring tensioning means may be used without deviating from the spirit of the invention.

When the capper head is in the raised, non-operative position of FIGS. 4, 6 and 8, the actuating lever 48 bears against the narrow upper end of cam bar 46 and results in heating elements 36 being maintained in their radial outward positions. As the capper head is lowered, however, actuating lever 48 rides down the inclined edge 47 of cam bar 46 and is moved circumferentially and thereby moves heating elements 36. This action can best be understood by referring to FIGS. 3, 5, and the dotted line portion of FIG. 8. It should be understood that means other than the illustrated cam bar can be used to actuate the rotatable ring and heater element mechanism.

As hereinbefore described, the individualcut sheets 14' of the shrink-film are folded down over and around cup 16 just prior to being heat shrunk. This is accomplished by utilizing a folding collar 51 attached to bottom plate 33 of capper head l7.'The folding collar 51 forms a thin walled hollow cylinder which engages the sheet 14 of shrink-film, held by grippers 23, 24, dislodges the sheet from the grippers'and folds it down and around the cup 16 prior to the inward radial movement of heaters 36, as best illustrated in FIGS. 6 and 7. As the capper head 17 is further lowered, the heating elements 36 move radially inwardly and contact the sheet 14' of shrink-film, positioned by the folding collar 51, thereby forming a heat shrunk band of film around the cup. i

It should be noted that the more surface area of the shrink-film and cup contacted by the heater elements 36, the more uniform and effective will be the heat shrunk band formed around the cup. The heater elements, therefore, have been provided with contoured inner faces 52 which conform to the configuration of the container to be capped, e.g., a conventional tapered cup 16. Thus, viewing FIGS. 6, 7 and 9, each surface 52 is concave and inclined in that they closely conform to the contour of the cups tapered side walls. A suitable electric heating coil 53 may be arranged within each heater element 36 and connected to a source of power by conductors 28 to heat the elements for effecting heat shrinking and sealing.

in addition to providing a heat shrunk band around the periphery of the cup side wall, it has been determined that the application of a small amount of heat to the top of the film will tend to shrink and draw the film taut over the mouth of the receptacle and eliminate any wrinkles that may otherwise form inthis area. This has been accomplished by providing a heated chamber within which the cup and shrink-film are positioned during the shrinking operation. The capper head 17 may be provided with a cover'54 made of a suitable heat conducting material. Heat from the heating elements 36 is conducted through the capper head 17 and into top cover 54 to confine and prevent the heat from escaping therefrom.

When the capper head 17 is in the lowered operative position with elements 36 in direct contact with the cup 16 and film l4, heated cover 54 will be disposed a short distance 55 from the top of the cup. Heated air within the chamber, plus heat radiated directly from cover 54, will combine to slightly shrink the film 14 over the mouth of the cup and remove any wrinkles from this area. Thus, all three ways of transferring heat are utilized in the present capper head, viz., conduction to form a heat shrunk band around the sides of a container; and convection and radiation to smooth wrinkles and draw the film taut over the mouth thereof. It is to be noted that the application of heat directly to the film, as hereinabove described, speeds up the shrinking thereof and, hence, the container capping operation.

It will be understood that various details of construction and arrangement of parts may be made without departing from the scope and spirit of the appended claims.

I claim:

1. An automatic shrink-film capping machine for forming caps of shrink-film over the open end of a container comprising in combination, a frame adapted to receive a container therein, capper head means in said frame axially aligned with said container, said capper head means being vertically movable from an elevated non-operative position to a lowered operative position, meansto position a sheet of plastic shrink-film over said container, and means to lower said capper head means relative to said sheet and container, means to fold said sheet over the top and sides of said container, a plurality of radially disposed heater elements within said capper head means, and means to move said heater elements radially inwardly when said capper head means is in said lowered, operative position, whereby said heater elements contact the film and the sides of said container to form a heat shrunk cap thereover.

2. A capping machine, as defined in claim 1, wherein said heater elements are contoured to conform to the sidewalls of the container to be capped.

3. A capping machine,'as defined in claim 2, wherein four heater elements are included.

'4. A capping machine, as defined in claim 1, wherein there is a switch means in said frame to sense the presence of a container arranged therein and actuate said capper head lowering means. v

5. A capping machine, as defined in claim 1, wherein there is a folding collar on the bottom of said capper head means to fold said sheetv of shrink-film over the top and sides of said container.

6. A capping machine, as defined in claim 1, wherein there is a heat conducting cover on'the top of said cap v per head means to form a heated chambertherein.

7. A capping machine, as defined in claim 6, wherein there is a gap maintained between said cover and said folded shrink-film when said capper head is in the lowered, operative position.

8. A capping machine, as defined in claim 1, wherein said means to move said heater elements comprises a ring rotatably attached to said capper head having upstanding pins thereon communicating with slots in said heater elements, radial guideways for said heating elements, whereby rotational movement of said ring is translated by said pins moving in said slots, into straight line radial movement of said heater elements. 

1. An automatic shrink-film capping machine for forming caps of shrink-film over the open end of a container comprising in combination, a frame adapted to receive a container therein, capper head means in said frame axially aligned with said container, said capper head means being vertically movable from an elevated non-operative position to a lowered operative position, means to position a sheet of plastic shrink-film over said container, and means to lower said capper head means relative to said sheet and container, means to fold said sheet over the top and sides of said container, a plurality of radially disposed heater elements within said capper head means, and means to move said heater elements radially inwardly when said capper head means is in said lowered, operative position, whereby said heater elements contact the film and the sides of said container to form a heat shrunk cap thereover.
 2. A capping machine, as defined in claim 1, wherein said heater elements are contoured to conform to the sidewalls of the container to be capped.
 3. A capping machine, as defined in claim 2, wherein four heater elements are included.
 4. A capping machine, as defined in claim 1, wherein there is a switch means in said frame to sense the presence of a container arranged therein and actuate said capper head lowering means.
 5. A capping machine, as defined in claim 1, wherein there is a folding collar on the bottom of said capper head means to fold said sheet of shrink-film over the top and sides of said container.
 6. A capping machine, as defined in claim 1, wherein there is a heat conducting cover on the top of said capper head means to form a heated chamber therein.
 7. A capping machine, as defined in claim 6, wherein there is a gap maintained between said cover and said folded shrink-film when said capper head is in the lowered, operative position.
 8. A capping machine, as defined in claim 1, wherein said means to move said heater elements comprises a ring rotatably attached to said capper head having upstanding pins thereon communicating with slots in said heater elements, radial guideways for said heating elements, whereby rotational movement of said ring is translated by said pins moving in said slots, into straight line radial movement of said heater elements. 